Weakened hydrogen bond connectivity promotes interfacial mass transfer for industrial level scalable biomass electrooxidation

Abstract

The 5-hydroxymethylfurfural electrooxidation reaction (HMFOR) has recently garnered significant attention in the field of biomass conversion. However, the sluggish kinetics of the HMFOR result in a low energy conversion efficiency. Herein, we identify the effect that hydrogen bond connectivity at the electrode–electrolyte interface has on the performance of the HMFOR. Through experimental tests and molecular dynamics simulations, we found that the inhomogeneous valence distribution due to the intrinsic electric field of the heterostructure catalyst can weaken the interfacial hydrogen-bonding connectivity under bias potential, which promotes the mass transfer of HMF during the reaction. Based on this, a Ni(OH)₂/Cu(OH)₂ heterostructure assembled using a simple wet-chemical method exhibited unprecedented performance with a current density of 1.3 A cm⁻² at a potential of 1.5 V. More importantly, the preparation of the Ni(OH)₂/Cu(OH)₂ material is scalable and it is continuously stable in an anion-exchange membrane electrolyzer for at least 380 h when 100 mM HMF solution was used as the fluid phase. We could simultaneously achieve scalable catalyst preparation, high current density, high yield and selectivity, high Faraday efficiency, and continuous stability for an industrial level HMFOR. This work provides a new perspective on enhancing the electrocatalytic oxidation of biomass-based substrates from the view of interfacial hydrogen bond connectivity.